Heat regulating method and apparatus



Patented Sept. 225, 1934.-

artnr srArss rmA'r assicurino METHOD AND l i k'Arrnmaa'rrIs My invention relates to furnaces and more particularly to a novel method and apparatus for automatically controlling the temperature within a furnace.

My invention contemplates the provision of means for automatically regulating the temperature conditions of a furnace whereby fluctuations in temperature will be immediately counteracted by variations in rate of .fuel liow to the furnace.

A further object of my invention is the provision of an electrically actuated furnace fuel control which automatically adjusts the fuel supply as the furnace temperature varies from a predetermined desired value. i

Another object of my invention is to provide a novel method and apparatus for controlling the temperature within a furnace whereby the fuel supply to the furnace isincreased or decreased in accordance with the diiference between an actual and a desired temperature, and as the temperature within the furnace approaches the desired temperature the increases or decreases in rate of supplying fuel are cut off prior to the attainment of the desired temperature, the temperature of the point of cut-od being made to differ from the desired temperature as the actual temperature differs from the desired temperature.

Other objects and advantages of the invention will be apparent as it is better understood from the following description taken in connection with the accompanying drawing, in which:

Figure 1 is a diagrammatic view of a furnace.

embodying the features of my invention;

Figure 2 is a view taken on the line 2-2 of..

- 16 are preferably pivoted to this actuating rod 90 Figure 1'; l

Figure 3 is a schematic wiring diagram of a temperature'responsive 'device 4adapted for, use in f connection with furnaces;

Figure 4 is a view taken on Figure'l; and

Figure 5 is a partial diagrammatic view of another embodiment of my invention.

I accomplish the foregoing objects and eliminate the diiculties of furnace regulation by manual or signal means by providing a'novel method and apparatu'srfor automatically controlling the fuel supply to a'furnace 1n the instant invention 1 provide a method whereby the rate of supthe line 4-4 of l plying fuel to a furnace is varied in accordance ture.

with the relationship existing between an actual and a desired temperature and these variations in rate of supplying fuel are cut off at sometime prior to the attainment of the desired tempera- These changes in rate of supplying fuel are preferably made in constant increments or decrements and the temperature of the point of cut-oif of variations in rate of supplying fuel to the furnace is preferably made to differ from. the desired temperature byr ay variable amount varying in accordance Withthe relative differencebetween the actual and the desired temperatures.v` By providing such. a novel method and apparatus for regulating and controlling the furnace temperature and the furnace fuel and/or air supply, errors due to the human factor are eliminated and the fuel and/or air is efficiently utilized so that just the proper rate of iiow of fuel and/or air is maintained to obtain the desired temperature.

My novel method of furnace temperature control may be applied to a furnace 11 illustrated 70 diagrammatically in the drawing. A supply line l2 is used to convey the fuel and/or air rfrom a source not shown to the furnace 1l. If desired two lines may be used to convey the fuel and air` to `the furnace, one being used for fuel in alliquid, gaseous form or any-.other suitable fuel in the mobile state and the other for air, in which case an auxiliary line 13 is provided. Thesev lines are provided at any convenient location with dampers or control valves 14. These con- .80 trol valves are preferably operated by a mechanism which normally does not entirely close the valves. The valves 14 are attached in any convenient manner to Valve operating means or arms K 16 provided at one end with slidable weights 1'7, 85 or means for providing the correct amount of counterbalancefor a valve arm operating means or actuating rod 18, to which the arms 16 are afxed in any suitable manner. The valve arms as at 19. l V By providing suitable means for actuating the rod 18 the position of the valve 14 may be ad- Yjusted in the line 12, or if two lines are used, in

the-lines 12 and 13 to obtain Varying flows of' 95 fuel and/or airv to the furnace. Moreover,

vchanges in rate of now of fuel should preferably be madey responsive to temperature changes in the vfurnace and some means of obtaining a change in rate of flow to correspond to a desired '100 temperature variation shouldbe provided. Ac-

-cordingly'I employ a means for determining'the Vil schematically in Fig. 3, in which the temperature changes in the furnace produce a current potential in the thermo-couple circuit.

This unknown potential is balanced against known potentials forming a potentiometer. When the known potential has been made equal to the thermo-couple potential the circuit is balanced and the galvanometer 27 shows nc deflection. An indicator or movable contact 29 moves in response tov-temperature changes in .theefurnace for. automatically balancing thehgalvanomf' eter and may be controlled by the galvanometer by any suitable means, for example, a pulley and belt mechanism 30. The operation of a pyroni: eter is well known by those skilleddn theartsand requires no further explanation."

In the practice of my invention I employ this pyrometer 24 to control suitable apparatus to carry out my novel method ,of .furnace tempera- L` ture control. Such a suitableiapparatus is provided by employing the indicator 29 or any-other"- temperature responsive means to control or to dri-veda 4means which -will providev movements proportional -to-:themovements of' -the indicator 29-and whichlwillvallow the setting of desired temperature:i This may be accomplished bypro`A l ,-:Jviding -reciprocable elements controlled -rorr'rthe'n indicaton 2Q-which may -be provided Y with means for'settingla-desired temperature by moving one reciprocable element with 'respect to thel other 011,@asindicated-l in 'the drawing; movable, ro-

@tatable or oscillatable elements orpulleys 3l 32A-may be -mounted= on a bolt -33i provided-with a nut-34 forvholdingtheassembled elements' in positionsand may-be attached, in any conven ient--manner'as' byf a bracket 36v andboits 37,A to

the-housing of the pyrometer 24; it is desirable;

in=fthe practice of my invention,`v that the pulleys 31 and 32 be adaptedto 'bef-rotatable or movabletogether-uponaction of'- the indicator 29 or-'be rotatable with respectl to eachother to obtain a setting of a desired' temperature.' Asmeansfor holding# the 4`pulleys -infriction-al engagement; I employa spring 38 heldl into engagement vvwith the-pulley'iB-lfbymaA nut 39 whicheprovides "a means `for adjustingv thetension'ofthe`springY 3,836Releasing the springl 3S`=by` any available means'provides 'a means for releasing the frictional engagement of A'the'pulleysand'A allowing themA to be rota-ted with Arespect to-leach other toy obtain settings-of Vtemperature,`

a 'graduated scalein degrees of' temperature around its-periphery and the other'is provided Y' with'fanindicatorl'l so that any desired temfbeingiattached to-'the `indicator-29and the other endepreferably-y given approximately fone' turn -f around.l afgroove 46 provided'on the pulley32- and aflixedf thereto any f suitable f manner: Y -The "1 which ts inf'a groove'44-one end being-- attached Y y l to -the pulley .32 YTand:l the@ other end `passing#conveniently operate they mechanism withlwhich" contact memberi46 andvaiii'xedl thereton' f l In the'practice ofimy in'vention employ-'thei imovement of this contact `member 46 to selec- Accordingly I provide contacts 47 and 48 which are adapted to be selectively engaged by the contact 46 upon movement thereof. The contacts 47 and 48 may be mounted in any suitable manner although they are preferably carried by a member 5l which may be provided with a groove 52 in which the movable contact 46 may ride. in order to cut off the variations in rate of supplying fuel prior to the attainment of the desired temperature; I" provide fior movement"V of the member 5l s that the contacts' 47 and 48 may be moved.relative to the contact member 46. As shown in the drawing, the contact member 46 is *in mid position between the contacts 47 and 48.-It=is=pr-eferable to make the contact mem V ber 46 slightly shorter than the distance between wise direction'iwill cause V'the contact 46 to en#V gage 'the contact48 while-the c'ontactslfl andA 47 l will be engaged if the pulley is rotated in 'a' clockwiseY direction;k and-*further that the de'- greeof rotation of the :pulley'3l' will change the point to which the contactf46 will move in eng'ag# ing the' contacts 47and` 48, thatis, for ekample'v a large clockwise movement of the pulley '31 will cause engagement between thelcontact '46"and the Contact 47 at apoint'closer to 'the aperture 45 than wil-la smaller clockwise movement of" the Apulley 31. Hence `rocking 'or rotation 4of 'the pulley 3K1 is relected in 'corresponding'lnovement ofthe contact 46 with respect to' the contacts 47 and 48` and similarly, movement" of the indicator 29 responding to' temperature cha'rliges in the furnace isreflected in corresponding'move# ment* of the'contact member 46.y These'contacts`vcontrol the operation 'of motor 'meansor motors 53v and `54. v"These'notors `0r prime movers 53A and 54 maybe Avofany suitable typeada'pted to govern `theiuel control valve 14, but a'r'e"p`referably of thev reversible' type', and 'althougliA they maybe arranged tooperate directly it is usually preferable to'utilizesome' m'ethodb'f speedreduction. They may be connected in any, convenient manner, although as indicated'in the""draw"ing vthey are wired' in parallel.' i Oneof'- the pulleys 31er 32 is'pr'cvided Vwith as"fo"r eXamplefmotor 54', may be arranged to means to be hereinafterv described.

Units comprising a suitable motor and' sint:

able speed reductionmean's are available and their operationrequires little explanationasY they are familiar'to'those skilled' in the art towhichY One of they I'noto'rs,

thisinventio-n pertains'.""A `casing 56 houses speed" reduction gears, arrangedffs thatfthe motors 53and'54 will`A drive these gears andv a'reducti'on `in speed of the motor will be available at the -outp'ut"shafto`f the'gears' as' for examplefthe shafts 57 and58.v This' speed reduction'i's pref? tors may be'used and the outputfshaft speeds of the worm gears will beof such"s'peedvjv as to they are associated.v y g Themember 5 -1 guidingly'supportihg the' consuitable :manner toy provide Yinovement ofthe erablyf'of such order that standard speed mo# contacts1 4v 'and 48. This" movement; 'fntrle conT 115g As the .indicator 29 moves to the right the pull tacts 47 and 48 cooperating with the contact member 46 provides a means for stopping the variations in rate of supplying fuel to the furnace. However, it is desirable that the movementl of the contacts 47 and 48 be such that the temperature at which the variations in the rate of supplying fuel is stopped differ from the desired temperature in varying amounts, and it is. preferable that the temperature of this pointof cutv offl in relationship to the desired temperature should vary as the 'difference betweenan actual and a desired temperature varies. To accomplish this the shaft 57 may be fitted withA a means for providing a reciprocating movement to the member 51 andV is accordingly tted with an eccentric or a cam 59.. The cam 59 may be of any shape adapted to transmit a reciprocating motion to the member 51 which may be-,provided Y with a curved or arcuate portion as at 55adapt ed to hook over or engage the cam 59. Moreover the member 51 may be placed in any position al-V though it is preferable that it be placed ina position approachingy the vertical and supported by a roller 60.

The output shaft 58 of the reversible motor 53 is provided with means for opening and closing the fuel and/or air control valves 14 and is accordingly connected to the rod 18 as by a connecting linkage including a crank 61 suitably attached to the shaft 58. A connecting member 62 may be pivoted to the crank 61 as at 63 and is preferably pivoted tov the rod 18 as at 64. It will be apparent that rotation of the motor 53 will operate the control valve 14. If desired the motor 54 may be eliminated and the cam v59 mounted on the output shaft of theV motor 53 at the crank 61 for stopping the motor 53 at the desired point. i

As has been mentioned, the motors 53 and 54 are preferably connected in parallel, as by conductors 66 and 67 which are connected to a suitable source of energy. VTheY conductor 66 passes to a lead 68 which is common to both motors and the conductor 67 is connected to the contact -v A'usually preferably that they operate at approximately the same speed for by such operation the rotation of the cam 59 will cause cut-off of the variation rate of supplying fuel to take place.

at the desired point. When the pulley 3l is ro- I tated with respect to the pulley 32 the setting of a desired temperature is obtained thereby and the contact member 46 moves in one direction or the other for example upwards, causing the contact 46 to engage the contact 48 thereby rotating the motors 53 and 54. The difference between the actual furnace temperature and the desired temperature will determine the amount of rotation of the pulley 31 necessary and hence the point at which the contact 46 will be engaged by the contact 48.

When the contacts 46 and 48 are engaged the motors rotate and the length of time of rotation of these motors is determined by the amount of lrotation of the pulley 31; and the motor 53 causes K rises, the increase being indicated in the movement of the indicator, in this case to the right.

leys 31 and 32, whichV are now in frictional engagement, will be rotated in a clockwise direction and as the temperature rises toward the desired point the contact member 46 will be moving downwardly/tending to break the engagement of the contacts 46 and 48. The rotation of the cam 59 is however reciprocating the member 51 tending to breakrthe engagement between the contacts 46 and 48 due to the fact that the member 5l is moving upwardly or in a direction opposite to that ofthe contact member 46. Thus the contacts 46 and 48 are movmg relative to each other and in` a direction opposite to each other, and this upward movement of the contact 48 causes theengagem-ent rbetween thecontacts 46 and 48 toY be broken prematurely or before itcan be broken by the downward movement of the contact 46, thus arresting the further increase of flow of fuel to the furnace as the motors are stopped by thisaction. Hence it will be apparent that the point of cut-off of increasein fuel supply is determined by the relative movement of the' contacts 46 and 48, and the cam 59 may be arranged to cut off the increase in fuel supply at such a point as to prevent overriding of the desired temperature. In a furnace temperature control apparatus itis usually desirable that the apparatus be arranged to control the temperature within very clos-e limits of the temperature for which the furnace has been set so that if for any reason the temperature within the furnace should change the control apparatus will immediately function to restore the desired temperature.

For example, if the temperature in the furnace vshould rise slightly above the desired point the indicator 29 willmove to the right. As the indicator'moves tothe right the pulleys 3l and 32,

tact member 46 is moving downward so that the contact member 46 engages the contact 47 thereby starting both motors 53 and 54.

Asfsoon as the contacts 46 and 47 come into engagement the `motor 54 starts moving the contact 47 downwardly so that the contacts 46 and 47 may be moving in the same direction. The rotation of the motor 54 is tending to close the control valve 14, tending to arrest any further increasesin furnace temperature and at some point the downward movement of the contact 46 may be arrested and may start -moving upwardly. Because of this relative movement between the contacts 46 and 47 their engagement is broken before the temperature in the furnace reaches the temperature for which the apparatus has been set, and thus the tendency for the control valve to be closed too much, so as to provide less than the proper amount of fuel, is eliminated. It will be observed that constant and close regu-- lation of the temperature of the furnace at the point for which the apparatus has been set is obtained.

It is evident that the apparatus, by which my novel method of furnace temperature control 1s Two motors may be used as before, preferably of rthe reversible type and preferably wired in parallel. One of the motors may be utilized tocontrol th-e fuel and/or supply valves 14 and the other to operate a setting dial graduated in degrees located preferably in the pyrometer. Accordingly the setting dial is mounted on a shaft 67, operatively connected by means of suitable linkage to the motor 54. The linkage may comprise an arm affixed to the shaft 67and a connectinglink69 piv'ote'd tothe arn`168 "as 'at' 71. The connecting linktmay be 'pivotedv to a crank 72 as at 73 secured tothe output shaft 57v of theI 5 reduction unit'56."

Onv the shaft 67 there may be also mounted a suitable switch orA commutator 74 Whichmay in` clude two conducting cam shaped 'segments 76 and 77. A brush or contact 78v may be'ar'rjan'ged to operate responsive to movements of 'the galvaf noineter as by mounting thei brush 78 'on the belt 30'and may be arranged so that it will make contact With the contacts 76 and 77 upon rotation of the commutator 74. f

It Will be apparent that the motor 53 Will, as

V,1; before controlithe'fuel and/or air valves '14, and

that the motor 54 through the contacts 76, 77 and 78 will control the length of time of operation of both motors, as the degree of rotation of the set' ting dial will determine the pointat which the :.f Contact 78 makes contact with the contacts 76 or 77, While the direction f rotation of themotorsv 53 and 54 Will be determined by which of the'contacts 76'and 77 is engaged by the contact73. The point of'cutoif of increases or decreases in rate of g,fuel and/or air supply may be varied to secure cut-off at the required point to prevent overriding the desired temperature; 'This may be accomplished by rotating thes'etting dial through an arc less than that required to set the desired tem- ,peratura so thatV the motors 53 and 54 may be stopped before the desired temperature is reached.

Tt will be apparent that 'I have provided apparatus extremely? sensitive to temperature variations and apparatus which will immediately function to ;yary the supply of fuel and/or air Whenever'the temperature of the furnace' variesfrorn Ythe temperature for whichv it hasbeen'set.A

It will furtherbe evident that I have provided 40 a novel-method anc-.apparatus for controlling the :temperature of a furnace `whereby the rate of `supplying fuel to'a furnace is variedin accordance with the relative difference between an actualan'd a desired temperature'and that the rate of supplying fuel are cut off at some temperrature point prior to the attainment'ofvthe"desired 4 reversible motors,

variations ini temperature, and that thedfferencebetween the4 temprature@ of the point'of cutoff and the desired tipraturehasbeen'made tofvary in accordance With the` relative difference betweenv the actual andthe desired temperature.

"While I have illustrated anddescribedaspeoinc embod'ifment of myinventon, manymodifications maybe made Without; departing from, the spirit of the'iiivention, and I do not Wish to vbe limitedto the'pr'eci's'e" details set' forth, but. desire to avail myself of allpharigevv'it'liinthe scope o f the ape pended claims; i' F l.`Ina furnace 'alpair ofsimrultaneously operable'reversiblemotors, arfuel control valve operableby'az said-motor, cam means controlled `bythe other said motor for stopping the firstsaid motor, associated pulleys rotatablein response to furnace tempslefues; iidwtch means @rable lov-said pulleys for starting lsaid motors.

Infamoto'r 'operated furnace'` fuel control apparatus, a fuel control valvelja pair of reversible Inotors, a reversiblel moto-r'being operatively con-` nected 'toV saiol control valve, associe-(tedv selective.. and reciprocable contact means eontrol'lingrsaid and manuall means for,@ClillstfA ing said V'selective YContact means relative4 toy said rec'iprocable: Contact Ineansin st'artingfsaid mo-V torsfthe other said reversible motor havingan eccentric` operatively connected `to said,l reciprocable"contactV` means to adjust said re'ciproeable contactV ineans relative to said selectivefcontact zneansin stopping sai'dmot'ors.

'3`; Inv an electrical furnace control apparatusga pyro'meter operable responsive to temperatures in said furnace, a ycontrolsir/,itch'having selective points of `Contact, means'respons'ivefto,variations in'the' indication of said pyroineter foractuarton of said switch including a rotatable indicator dialV forv operating said control switch, a pairof motors controlled by said switch, oneV of said motors'con7'- trolling the fuel supplyv t'o said furnace and the other Icooperating With said'rotatable ,indicator dial in 'controlling thev 'operation of saidA switch and 'said first mentioned motor.

' HENRYA. DREFFEIN.` 

